ultiple Choice (10 marks) entity the letter of the choice that best completes the statement or answers the question 13. The speed of any mechanical wave as it propagates through a medium is dependent mainly on the a. frequency of the wave source d. type of medium through which it travels b. wavelength e. amplitude C. period of the wave 14. If a sound has an intensity of 3.0W/m^2 Find its intensity if the observer were to move three times as far away from the source. a. 0.33W/m^2 d. 27W/m^2 b. 1.0W/m^2 e 3.0times 10^2W/m^2 C. 9.0W/m^2 15. Which of the following is not an application of the reflection of sound? a. Ultrasound imaging d. resonance b SONAR e. they are all applications of reflection C. echolocation 16. Which statement best describes what will occur at the barrier between th medium, shown below? incident pulse __ a. The reflected pulse will be in upright and the transmitted pulse will be inverted. b. The reflected pulse will be inverted and the transmitted pulse will be upright C. Both the reflected and transmitted pulses will be upright. d. Both the reflected and transmitted pulses will be inverted e. All of the wave energy will be reflected and inverted, and there will be no transmission. 17. An ambulance is approaching a stationary observer. For the observer , the apparent frequency of the siren compared to the actual frequency of the siren a. increases or decreases depending on the speed of the ambulance b. resonates C. decreases d. stays the same e. increases 8. A person tuning a guitar strikes a tuning fork with a frequency of 384 Hz simultaneously as a guitar string is plucked. If 15 beats are heard in 5.0 s, the frequency of the string is a. 369 Hz d. 381 Hzor 387 Hz

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ultiple Choice (10 marks) entity the letter of the choice that best completes the statement or answers the question 13. The speed of any mechanical wave as it propagates through a medium is dependent mainly on the a. frequency of the wave source d. type of medium through which it travels b. wavelength e. amplitude C. period of the wave 14. If a sound has an intensity of 3.0W/m^2 Find its intensity if the observer were to move three times as far away from the source. a. 0.33W/m^2 d. 27W/m^2 b. 1.0W/m^2 e 3.0times 10^2W/m^2 C. 9.0W/m^2 15. Which of the following is not an application of the reflection of sound? a. Ultrasound imaging d. resonance b SONAR e. they are all applications of reflection C. echolocation 16. Which statement best describes what will occur at the barrier between th medium, shown below? incident pulse __ a. The reflected pulse will be in upright and the transmitted pulse will be inverted. b. The reflected pulse will be inverted and the transmitted pulse will be upright C. Both the reflected and transmitted pulses will be upright. d. Both the reflected and transmitted pulses will be inverted e. All of the wave energy will be reflected and inverted, and there will be no transmission. 17. An ambulance is approaching a stationary observer. For the observer , the apparent frequency of the siren compared to the actual frequency of the siren a. increases or decreases depending on the speed of the ambulance b. resonates C. decreases d. stays the same e. increases 8. A person tuning a guitar strikes a tuning fork with a frequency of 384 Hz simultaneously as a guitar string is plucked. If 15 beats are heard in 5.0 s, the frequency of the string is a. 369 Hz d. 381 Hzor 387 Hz

Answer 1

* **13. d. type of medium through which it travels**The speed of a mechanical wave depends primarily on the properties (elasticity and inertia) of the medium it travels through.* **14. a. 0.33 W/m²**Sound intensity follows the inverse square law. If the distance triples, the intensity decreases by a factor of 3² = 9. So, 3.0 W/m² / 9 = 0.33 W/m².* **15. d. resonance**Resonance is about the amplification of sound waves at specific frequencies due to the natural vibrations of an object, not the reflection of sound.* **16. c. Both the reflected and transmitted pulses will be upright.**The pulse is moving from a more dense medium to a less dense medium. In this case, the reflected pulse remains upright, and the transmitted pulse is also upright.* **17. e. increases**Due to the Doppler effect, as the source of a sound (the ambulance) moves toward a stationary observer, the apparent frequency increases. The waves are effectively compressed, leading to a higher perceived frequency.* **18. d. 381 Hz or 387 Hz**The beat frequency is 15 beats / 5.0 s = 3 Hz. This means the guitar string's frequency is either 3 Hz higher or 3 Hz lower than the tuning fork's frequency (384 Hz). Therefore, the possible frequencies are 384 Hz + 3 Hz = 387 Hz or 384 Hz - 3 Hz = 381 Hz.

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